Pitch adjusting mechanism



Jan. 24, 1950 T. H. TROLLER FITCH ADJUSTING MECHANISM 2 Sheets-Sheet lFiled May 27, 1944 HVVENIUR.

www ccd2 Jan 24, 1950 l T. H. TROLLER 2,495,433

FITCH ADJUSTING MECHANISM Filed May 27, 1944 2 Sheets-Sheet 2 //kU//AD/efcnon/ of (brano/V Y MMM Patented Jan. 24,1950

UNITED STATES PATENT l OFFICE FITCH ADJUS'HNG a eorporatlon ofPennsylvania my 27, 1944. Schl No. 537,567

2 Claima- (CL 17o-160.16)

l The invention relates -in general to variab pitch propellers and moreparticularly to a mechanism for adiusting the pitch of the propellerblades of fans.

An object of the invention is the provision of an improved pitchadjusting mechanism which is simple in construction, easy to andoperable to vary the pitch of the blades while the fan is operating.

Another object of the invention is the provision of an improved pitchadjusting mechanism including a rotatably mounted disc member having anannular face adapted to press against arms which are connected to theblades and'which when the arms are moved provide for rotating theblades.

Another object of the invention is the provision of an improved variablepitch propeller lmounted upon a drive shaft with the blades actuated tovarious pitch angles by an axially movable disc member which is carriedby the shaft and which presses against arms connected to the blades forrotating the blades to vary their pitch angle.

Another object of the invention is the provision of improved pitchadjusting mechanism including means for individually adjusting the pitchangle of the blades for a fixed axial position of .the actuating discmember which controls the joint operation of all the blades.

Another object of the invention is the provision of an improved pitchadjusting including anaxially movable disc member which controls thepitch of the blades and which does not interfere with the assembling ordismantling of the blades or associated parts.

Another object of the invention is the provision of an improved pitchadjusting mechanism including spring means connected to each of the armsof the blades for exerting a force to oppose the movement of the arms bythe actuating disc member.

Other objects and a fuller understanding of `the invention may be had byreferring to the following description and claims, taken in conjunctionwi-th the accompanying drawings. in which:

Figure 1 is a longitudinal sectional view of an embodiment of theinvention taken along the line I-I of Figure 3 and with parts shown inelevation and portions of some parts broken away;

2 the line 3 3 of Figure 1, with the noselike cover removed to show theactuating disc member which presses against and operates the armsconnected to the shanks of the propeller blades for rotating thepropeller blades for varying the pitch thereof; and

Fgureiisaviewtakenalongthelinel-Iof Figure 2.

My invention is being illustrated and described in connection with avariable pitch fan but -it is to be understood that it applies tovariable pitch blades of all kinds.

As illustrated in the drawing, the variable pitch fan is designatedgenerally by the reference character I I and is arranged to be rotatablymounted within an outer annular duct I0 which may be connected in anysuitable duct system for distributing the fan driven air. The variablepitch fan II may be driven by any suitable means and as shown in thedrawings, the fan is driven by an electric motor Il which may be mountedwithin an inner annular housing I5 which is supported substantiallyconcentric within the outer annular duct I0 by means of stationary guidevanes I6.

The variable pitch fan II comprises, generally,-

a rim I2 and a plurality of blades I3 having shank portions 24 rotatablymounted within the rim I2 by means of ball bearing units 25 whereby theblades may be easily turned by the pitch adjusting mechanism. The rim I2is provided with a web I8 which is arranged to be mounted upon the motorshaft I1 by means of a nut I9. As is manifest, the motor shaft I1supports and drives the complete fan assembly which greatly facilitatesthe mounting of the variable pitch fan within the `outer annual duct I0.

Adjustably mounted upon the inner end of each of the shank portions 2lof the fan blades is an actuating arm 21. As shown best in Figure 4, theactuating arms 21 extend outwardly from the shank portions 24 and arearranged to be actuated by an actuating disc member 2B which isrotatably mounted upon a shaft extension 3l of the motor shaft I1. Asshown in Figure 1, the lefthand side of` the actuating disc member 29may be provided with a wear face plate 3B which presses against the endsof the actuating arms 21 for varying the pitch of the fan blades I3. Theactuating arms 21 are adjustably mounted upon the shank portions bymeans of nuts 26. The propeller blades I3 may be each individuallyadjusted with respect to a xed axial position of the actuating discmember 29 by loosening the nuts 2i and turning the blades to theircorrect position, after which the nuts 26 may again be the actuatingdisc member 29.

3 tightened. Consequently, as the actuating disc member 29 is axiallymoved upon the shaft extension 3|, the blades turn simultaneously tovary their pitch angles. A spring 28 is associated with each of theactutaing arms 21 to exert a force in opposition to the movement of thearms by the actuating disc member 29. As shown best in Figures 2 and 4,one end of the spring 28 is connected to the actuating arm 21 and theother end of the spring is arranged to fit against the web I8 whichsupports the rim of the variable pitch fan. Accordingly, the springs 28hold the actuating arm against the wear face plate 30 of Under runningconditions, the action of the centrifugal forces and/or the air forcesupon the blades is such as to constrain the ends of the actuating arm 21against the wear face plate 30, in addition to the spring pressure.

The axially reciprocal movements of the actuating disc member 29 isgoverned by a control rod 35 which is actuated by a control lever 36having one end 39 pivotally connected to one side of the outer annularduct IU and having its other end 48 extending externally of the outerannular duct I for external actuation. The control rod 35 extendsthrough an opening 38 in a nose-like cover 31 which may be suitablyconnected to the forward edge of the rim I2, such for example, as by acrimped edge 4I which resiliently engages a bead 42 provided on theinternal surface of the rim of the fan. As illustrated, the control rod35 is connected to the hollow hub 32 of the actuating disc member 29 bymeans of a ball bearing unit 34, whereby the actuating disc member 29may rotate upon the shaft extension 3| as the variable pitch fan isoperated. A bushing 33 is mounted inside of the hollow hub 32 and isarranged to provide a bearing surface with the extension shaft 3|.

In operation, the pitch of the fan blades is ad- It is noted thattheactuating disc member 21 constitutes a very simple construction forvaryinl the pitch of the fan blades and affords an eas: method ofassembling the units inasmuch as therl is no necessity for the radialalignment of thu actuating arms 21 with respect to the wear fam plate30.

Although I have described my invention wltt a certain degree ofparticularity, it is understoocl that the present disclosure has beenmade onli by way of example and that numerous changes in the details ofconstruction and the combination and arrangement of parts may beresorted tc without departing from the spirit and the scope of theinvention as hereinafter claimed.

What I claim is:

1. A variable pitch propeller comprising a rotatably supported bodyhaving antifriction devices arranged thereon at points spacedcircumferentially about the same and blades rotatably supported by saidantifriction devices for turning on axes extending radially of said bodybut fixed against movement in either direction longitudinally of suchaxes, said blades so formed that the action of centrifugal force and ofthe air thereon as said body rotates produce a resultant torquesufficient to turn said blades on said axes,

arms fixed with respect to each of said blades and justably Varied bymoving the control lever 36 f which in turn axially positions theactuating disc member 29 for holding the blades at a predetermined pitchangle as determined by the setting of the control lever 36.` The pitchof the blades may be varied While the fan is rotating and any suitablemeans may be employed to hold the outer end 40 of the control lever in afixed position after the pitch of the blades has once been set oradjusted. During rotation of the fan, the centrifugal forces and/or thepressure of the air upon the blades I3 is such as to cause the actuatingarms 21 to be pressed against the wear face plate 30 of the actuatingdisc member 29. When the fan is idle, the springs 28 continue to biasthe ends of the actuating arms 21 against the Wear face plate 30 of theactuating disc member 29. The springs 28 may be dispensed With becausejust as soon as the fan has started to rotate the centrifugal forces,and/or the air forces, cause the blades to rotate in such direction asto cause the actuating arms 21 to press against the wear face plate 3Bof the actuating disc member 29. In other words, should the actuatingarms 21 be not contacting the wear face plate 30 when the fan is idle,they will beimmediately turned by the centrifugal forces and! or thepressure of the air acting against the fan blades I3 to immediatelypress them against the wear face plate 30. The ball bearing units 25constitute antifriction bearings whereby the fan blades may be easilyturned by the pitch adjusting mechanism when the fan blades arerotating.

projecting at least generally radially with respect to said axes, andarm angle controlling means including a member supported in coaxialrelation with said body for rotation relative to the latter and formovement towards and from the latter along its axis of rotation, andhaving an annular surface on one face thereof with which said arms arefrictionally engageable whereby changes in position of said member alonga line including its axis of rotation, through the action of saidsurface on said arms, may change the angle of said blades to said body.

2. A variable pitch propeller comprising a rotatably supported bodyhaving antifriction devices arranged thereon at points spacedcircumferentially about the same and with their axes in a common planeand blades held against radial movement by said antifriction devices butjournaled by the latter for turning on axes extending radially of saidbody, said blades so formed that the action of centrifugal force and ofthe air thereon as said body rotates produce a resultant torquesufficient to turn said blades on said axes, arms adjustably secured infixed relation to each of said blades and projecting at least generallyradially with respect to said axes, and a member supported in coaxialrelation with said body and turnable on its axis relative to said bodyand movable relative to the latter along the line of its axis ofrotation, and having an annular surface on one face thereof with whichsaid arms are frictionally engageable and which constitutes the solecontact with the latter of said member, and means for moving said membertowards and from said plane whereby changes in position of said memberalong a line including its axis of rotation, through the action of saidsurface on said arms, may change the angle of said blades to said body.

THEODOR H. TROLLER.

REFERENCES CITED The following references are of record in the le ofthis patent:

(References on following page) Number :Mamas Number 0 Name Date BellmanNov. 23, 1937 Williams Apr. 13, 1943 Dewey et al Apr. 20, 1943 BebingerJune 6, 1944 Stepanot! Sept. 12, 1944 Bebinger Sept. 19, 1944 Adams etal. Dec. 4, 1945

